Brian Somerday and Joe Ronevich (both in Sandia’s Hydrogen and Combustion Technology Dept.) won the Best Poster Award for their presentation “Assessing Hydrogen Pipeline Reliability: Quantifying Susceptibility of Pipeline Steels to Hydrogen Gas-Accelerated Fatigue Crack Growth” at the ASME 12th Fuel Cell Science, Engineering and Technology Conference in Boston, Massachusetts.

LabNews_Ken_Lee_08_(web)One pathway for delivering H2 from centralized production facilities involves transmission/distribution pipelines. It is anticipated that natural gas pipeline technologies will be adopted for long-distance H2 transmission, i.e., steel pipe joined by welds.

Assessing the reliability of steel H2 transmission pipelines must consider fatigue crack growth aided by H2 embrittlement. This study’s objective was to measure fatigue crack growth rate (da/dN) vs. stress-intensity factor range (dK) relationships for X52 and X65 pipe steels and their welds in 21 MPa H2 gas. Following this onset of H2-accelerated crack growth, the absolute crack growth rates are similar for the base metal and welds.

These results were not necessarily expected, because steel microstructure varies significantly in the distinct material regions. Results from testing base metal in H2 gas with controlled levels of oxygen (10–1000 vppm) demonstrate that the transition to H2-accelerated crack growth strongly depends on O2 concentration, i.e., the dK level at the onset of acceleration increases as the O2 concentration increases.

This work was supported by the DOE Fuel Cell Technologies Office within DOE-EERE.